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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 2:39 am
Please don't warn me for posting link
http://physics.stackexchange.com/questio...wn-gravity
Correct me if i'm wrong but doesn't this thread on stackexchange say that heavier objects do fall faster than lighter objects?
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 3:57 am
The gravity you exert upon the Earth is incredibly miniscule compared to the gravity the Earth exerts upon you, so the Earth draws you to it.
Lighter objects don't fall faster because gravity doesn't operate as a competition between the two gravitational bodies; gravity works on the principle of center of gravity, which means that in reality the pull gets averaged somewhere in between, and often in empty space. That isn't the case with the Earth and a human body: the center of gravity in that system is much closer to the center of the Earth than it is to you, so you feel it as a pull, stopped by the ground beneath your feet.
From your link:
Quote:The accepted answer says that the difference in the times between two objects could be on the order of 1 part in a trillion trillion. So there won't be much to measure, and according to human perception & instrumentation we would always call it "simultaneous." Dropping the items together would take even less time.
Such a minor discrepancy would not be perceptible to even the finest-tuned measuring instrument.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 4:11 am
(This post was last modified: August 2, 2015 at 4:28 am by Alex K.)
But yes, a heavier object would attract earth more and reach it sooner because earth approaches it.
The falling at the same speed is an idealized limit
mass(body)/mass(earth)->0
*and*
size(body)/distance from center of earth ->0.
The deviations though are as incredibly tiny as these ratios or even higher powers of them. The second of those arises already in Newtonian physics bc. the idealized situation that gravity acts on the "center of gravity" is only applicable if the acceleration of gravity is exactly the same throughout the objecf.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 8:24 am
Gravity itself doesn't exist, however there are three models that approximate what we (or rather Newton) call gravity with varying degrees of success. Newtonian Mechanics sent man to the moon, put countless Satellites into orbit, and it can also send us to Mars. It's not right thought, Newton was right when he said that people wouldn't believe in a force that moves at infinite speed because it doesn't exist as a force, ergo "gravity" does not exist. You could also use Special Relativity (or General Relativity) to do those things I mentioned - but it's not necessary and overly complicated to achieve the same result of using Newtonian Mechanics. On the other hand you couldn't use Quantum Physics to do it.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 10:01 am
(This post was last modified: August 2, 2015 at 10:01 am by Alex K.)
Aractus, you confuse me. In *general relativity* there's no force of gravity, only geodesic motion through spacetime. In Newtonian physics, there is an instantaneous force.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 10:51 am
Can someone tell me why a "heavier" object would "fall" faster than a lighter object due to "gravitational pull"? (According to the link i posted?)
P.S. I don't know shit about physics so i put quotes on random words.Just saying.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 11:19 am
With gravity alone, a feather falls at the same speed as a rock. You forget that there is air (a fluid) in the atmosphere and that offers more drag to a feather, than a rock.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 11:39 am
(August 2, 2015 at 10:51 am)pool Wrote: Can someone tell me why a "heavier" object would "fall" faster than a lighter object due to "gravitational pull"? (According to the link i posted?)
P.S. I don't know shit about physics so i put quotes on random words.Just saying.
If you have a light object, it just gets attracted by earth. A really heavy object also vice versa attracts earth, and earth goes up towards the object a tiny bit, while the object goes down at the same time. Because of that, Earth and object approach each other a bit quicker.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 8:57 pm
(August 2, 2015 at 8:24 am)Aractus Wrote: Gravity itself doesn't exist
Tell that to the apple that fell on my head.
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RE: Is Gravity acting upwards or downwards?
August 2, 2015 at 9:02 pm
(This post was last modified: August 2, 2015 at 9:02 pm by IATIA.)
(August 1, 2015 at 5:22 am)BrianSoddingBoru4 Wrote: You're confusing work (pushing the two masses) with acceleration. When objects are accelerating due to gravity, the mass of the object doesn't matter. Galileo demonstrated this by dropping a cannon ball and a bullet from a height, and they hit the ground at the same time. So no, gravity doesn't 'push' or 'pull' either upwards or downwards - is an attractive force between two masses.
Boru
Actually, if one considers the gravitational pull of the cannon ball and the bullet, the cannon ball must fall faster, albeit a negligible difference in that experiment.
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